Polypropylene film is usually produced by the bubble or blown tube process or by a draft and tentering process. In each process, the polypropylene is continually produced on a very wide sheet which may be, for example, 1-3 meters wide and perhaps as thin as from 3.0 to 25 microns. For use in electrical capacitors, this film sheet is usually simultaneously slit to a number of smaller widths, and this slitting takes place as an adjunct to the film production equipment where the slitting mechanism receives film as produced from the film production equipment. It is preferred to slit the film directly from the mill roll simultaneously into as many as thirty-two or more strips which are also simultaneously wound on winding cores driven by a common mandrel to provide suitable film bobbins. Slip clutches are usually provided at a drive means between the driving mandrel and each of the winding cores. Simultaneous winding of plural film bobbins gives rise to a number of major problems such as film tension control and bobbin alignment. Variations in film thicknesses, i.e., off gauge conditions, adversely affect film tension, which for very narrow width film strips require quite precise limitations. The normal force which is usually necessary to generate the required friction for friction drive through slip clutches must ordinarily be applied to the ends of each of the plurality of cores, and this results in a general misalignment from core to core or bobbin to bobbin which is reflected in an oscillation of the tension applied to the narrow webs. This oscillation is often so great as cause the tension to vary by as much as 50 percent thus resulting in poor bobbin edges and generally lack of control over the winding process.